1. Field of the Invention
The present invention relates to a protective device resisting the impact of projectiles and fragments or splinters from explosions, which is intended more particularly for the protection of motor vehicles.
2. Description of the Prior Art
Several solutions have already been proposed for forming armor plating devices which, in almost all cases, have a composite laminated structure having at least one layer of inorganic (or natural) fibers, such as glass fibers, or organic (or synthetic) fibers, such as polyamide fibers ("NYLON") and especially aromatic polyamide ("KELVAR"), these latter being pratically universally used in the manufacture of ballistic protective devices, because of the high specific mechanical resistance, per unit of mass, of "KEVLAR" (which is a well known trademark registered by DUPONT DE NEMOURS) which is five times greater than the specific resistance of steel and double the specific resistance of "NYLON", "KEVLAR" also having the property of absorbing large amounts of kinetic energy.
By way of examples of solutions already proposed, a certain number of patents may be mentioned whose object is briefly recalled hereafter.
The VALLCORBA TURA, FR No. 2 348 991, relates to a textile foil for making cloths resistant to shocks and explosions, which is formed by an aramide (or aromatic polyamide) particularly KEVLAR, from 500 to 2500 deniers, and in particular 1000 deniers, woven with a simple cloth weave and covered in the mass, said filament being fixed firmly by coating with at least one impermeable resin face by passing it through a gelification tunnel, from which it leaves ready for making bullet-proof jackets, for example.
For the bullet-proof jacket to be efficient, the tissue is folded back on itself, which gives a laminated structure which may comprise a maximum number of 30 to 40 folds, ensuring protection against the impact of projectiles in the case of war and combats, explosions (dynamite), hunting as a sport.
Anti-explosion blankets may also be formed.
Between the successive layers of aramide fibers can be disposed free aramide fibers or any other type of refractory fibers such as "FIBERFRAX", "KAOXOOL", "TRITON", "CERAFIBER", "REFRASIL", etc. . . . , the inclusion of these free fibers being however not indispensable.
The BOTTINI et al. patent FR. No. 2 402 855, relates to a composite bullet-proof material, which may be formed as flat or curved foil as well as hollow bodies of complex form. It is composed of a plurality of aromatic polyamide fiber fabrics (ballistic "NYLON"), some at least of which are of ordinary "linen" type and others of the "batavia" type, each being impregnated with unsaturated polyester resins, which fabrics are superimposed on each other one by one or in groups, the mutual association being obtained at high pressure depending on the desired shape. In the case where only two fabrics of the above-mentioned type are used, the tissues of the "batavia" group are superimposed parallel or perpendicularly to the adjacent "linen" fabrics.
This patent corresponds to U.S. Pat. No. 4,200,677.
The Patent of the INSTITUT FRANCO-ALLEMAND DE RECHERCHES DE SAINT-LOUIS, FR. No. 2 425 046, relates to an armor plating device proof against projectiles and formed by a first plate exposed to the impact of the projectiles and made from a hard material, such as steel, whose thickness is greater than or equal to 0.3 times the caliber of the projectiles from which the armor plating device is to protect and by a second plate made from laminated material with low delaminating energy, whose thickness is at least equal to twice the caliber of the projectiles and is formed of inorganic fibers, such as glass fibers, or organic fibers, such as aromatic polyamide fibers (or aramide fibers), which fibers are bonded together by a soft resin, that is to say manufactured with a small amount of hardener, such a polyester resin, or are bonded by means of a natural or synthetic elastomer.
The two plates are assembled by bonding or by continuous or discontinuous mechanical means.
The IMI KYNOCH LTD Patent, FR No. 2 443 397, relates to a receptacle for storing dangerous materials, for example explosives, whose wall has a laminated structure comprising at least one relatively rigid layer, made from a plastic material, particularly a heat setting material, reinforced with fibers, particularly glass or polyamide fibers, and at least one elastomer layer, made more particularly from chlorosulfonated polyethylene, the rigid layer being closer to the inside of the receptacle than the elastomer layer.
In the case where the wall of the receptacle comprises several rigid elastomer layers, they are disposed alternately.
The laminated structure may also include an external metal layer.
The Patent of the SOCIETE NATIONAL DES POUDRES ET EXPLOSIFS, FR No. 2 469 277, relates to a device for protecting against shocks, due more particularly to the impact of a bullet or of fragments projected by an explosion, or else due to collisions between two bodies, for example two vehicles.
This device is of the type having laminated structure formed of superimposed layers of basic inorganic fiber fabrics, such as glass fibers or organic fibers, such as aromatic polyamide or aramide ("KEVLAR") fibers and an impregnating resin, particularly polyester or polyepoxide. This Patent claims the use in the protective device of the above-mentioned type of thermosetting or thermoplastic viscoelastic resin having a loss factor between 0.5 and 1.5, a modulus of elasticity between 10.sup.6 and 10.sup.9 N/m.sup.2, at a frequency of 100 Hz and at the temperature of use.
The proportion by weight of viscoelastic resin, with respect to the total weight of the protective device, is between:
10% and 30%, and preferably between 15% and 24%, in the case of forming light armor plating, or PA1 40% and 80% in the case of forming motor vehicle bumpers. PA1 a plate made from hard material causing the projectile to explode, directed on the firing side, PA1 a packing material decelerating the projectile, disposed on the rear face of this plate, and PA1 a layer with a high elongation at rupture, disposed on the front face of said plate. PA1 a plurality of ballistic foils (namely, resisting penetration by high speed projectiles) forming ballistic fibers, PA1 a dressing material, and PA1 a connecting material which bonds itself imperfectly to this dressing material. PA1 a honeycomb matrix which is obtained by heating and compressing said thermoplastic resin and which forms a 3-dimensional support, PA1 textile material layers formed by noble synthetic fibers, such as carbon, aramide, boron or similar fibers, which have exceptionally high mechanical properties and which are interlaced and contained freely in the cavities of said honeycomb structure and incapsulated by these cavities, i.e. the fibers are free to slide along the corresponding cavity. PA1 on the one hand, that, for forming flexible structures, particularly adapted to the formation of bullet-proof jackets, one is limited to the use of textile foils folded on themselves (cf. the VALLCORBA TURA Patent), however this solution is not suitable for forming armor plating for motor vehicles particularly, and PA1 on the other hand, that the adaptation of textile foils to the formation of armor plating devices requires the cooperation with plates or layers of a certain rigidity, the textile foils being almost generally impregnated with a resinous or elastomer bonding agent (only the Patent IMI/KYNOCH LTD describes a protection device whose laminated structure has at least one layer formed completely of elastomer, but also this latter cooperates with at least one rigid layer). PA1 in so far as the shaping to curved supports is concerned, this is only possible by having available a special mold, which is generally expensive, and whose use is justified essentially in the case of large-scale production, PA1 in so far as the cutting up of the pieces is concerned, it is difficult, which requires tools which are also special, such as diamond-tipped saw teeth, high pressure water jet devices or laser devices, PA1 in so far as the dimensions of the pieces are concerned, they are available in a relatively limited range, particularly because of the cutting out problems, PA1 in so far as the hygiene and work safety conditions are concerned, they imply the respect of strict standards because of the presence of volatile resins, and PA1 in so far as the manufacture of the pieces is concerned, it takes place in the presses or in autoclaves, which involves a high number of manual operations, particularly due to the superimposition of the layers of these stratified structure pieces, and so long periods of immobilization of the machines which raises the energy cost. PA1 it is adapted to be shaped manually to any metal or nonmetal support, curved or not, PA1 for equal performances, a considerable gain in weight is obtained and so reduction of the cost of the material required, PA1 cutting out is readily achieved, using ordinary cutting tools, such as a scalpel, cutter and similar, PA1 the manufacturing and application times are short, the manufacture being continuous. PA1 if perforation of the armor plating is total, no delamination is observed; PA1 if the perforation is partial, the delamination appears in a point situated between 50 and 70% of the thickness and deformation of the rear part of the device is small, whereas PA1 on the other hand, with modules having a low adherence film, i.e. between 5.10.sup.2 N/m and 29.10.sup.2 N/m and high elongation, penetration is partial, delamination appears at a point situated between 10 and 40% of the thickness and deformation of the rear part of the device is great. PA1 on the one hand, to confirming the decisive role of delamination in the absorption of the kinetic energy of the projectile, the stopping of which is determined by the nature and thickness of the elastomer film; and PA1 on the other hand, to thinking that the maximum stress causing the rupture of the threads is situated in the front face of the device, so that as the projectile penetrates into the armor plating, formed particularly by two superimposed modules of the invention, and is crushed, the movement of the material behind the transverse wave loads the threads of the secondary module and unloads the threads of the primary module. PA1 a first module placed on the front face and so advantageously formed of a fabric with a relatively high number of threads and having a high warp and weft resistance, whose sizing is between 1100 and 1680 dtex, whose resistance to rupture is greater than or equal to 186.10.sup.2 N/m of length, and in which the number of warp and weft threads is greater than 10.5; and PA1 a second module placed at the rear face, and so advantegously formed of a fabric having a lower resistance and a reduced number of warp and weft threads, whose sizing is between 1680 dtex and 3300 dtex, whose resistance is at least equal to 137.10.sup.3 N/m, and in which the number of warp and weft threads is greater than or equal to 3.7. PA1 in the absence of bonding, when a projectile impacts the metal part, a part of the longitudinal wave is diffused at high speed in the metal sheet without being decelerated, which reduces the stresses in the primary modules; PA1 when the metal sheet is heavily bonded to the flexible and modular armor plating of the invention, it strongly resists the advance of the projectile, which is thus slowed down; the flexible armor plating then undergoes considerable deformation which tends to better distribute the stress in the threads, whereas the deformation of the metal sheet loads the threads of the primary module over a larger zone. PA1 case A corresponds to a device having a mass per m.sup.2 of 3.3 kg/m.sup.2 and formed by a module: PA1 case B corresponds to a device having a mass to the m.sup.2 of 4.75 kg/m.sup.2 and formed by: PA1 case C corresponds to a device having a mass to the m.sup.2 of 6 kg/m.sup.2 and formed by:
The APPRICH Patent, FR No. 2 506 447, relates to armor plating for wall elements, particularly for the metal parts of the underneath of motor vehicles, for protecting against the action of explosive devices, including at least one layer of a coherent fiber mat impregnated with resin.
The fibers may be wholly aramide (aromatic polyamides) fibers and in particular "KEVLAR" fibers.
In the case where said mat is made only partially from aramide fibers, it may also comprise cotton fibers or polyamide fibers.
In each case, the mat may be formed by a fabric having several layers of warp threads and weft threads, connected with each other.
The impregnating resin is a resin with one or more components, in particular a polyurethane, polyethylene or polyvinyl chloride resin.
The AEROJET Patent, FR No. 1 605 066, relates to a material resisting shocks, whose resistance to penetration/weight ratio is exceptionally high and which may be used for forming breast plates for human beings or armor plating for air transport apparatus, personnel transport devices, etc. . . .
The material proposed includes several bonded layers of a material formed by interlacing glass fibers, particularly in the form of roves, and "NYLON", impregnated with resin, particularly polyester, epoxy or phenolic rubber.
The relative proportions by weight of the glass and "NYLON" fibers are between 90 parts of glass and 10 parts of "NYLON", and 10 parts of glass and 90 parts "NYLON".
The results of testing for resistance to shocks of this combination of fibers are better than the results obtained with one or other type of fibers used separately.
The said shock resistive material may also include an external surface layer of glass, alumina, boron carbide, silicon carbide, etc . . .
The Patent MAN MASCHINENFABRIK, DR No. 2 522 404, relates to an armor plating element in the form of a plate, of the type formed by:
According to this patent, the layer with high elongation at rupture is made from polyurethane, the hard material plate is made from sintered aluminium oxide or boron carbide ceramic and the backing material is a textile fiber fabric, particularly aromatic polyamide fibers, formed by several loosely superimposed layers and only weakly bonded together.
The packing material may be coated upon one side with said hard material and protected against humidity, in the zone not covered with this hard material, by hardenable synthetic impregnating resins.
The American Patent MEDLIN, U.S. Pat. No. 4,352,316, relates to armor plated vehicles with light armor plating, having the appearance of normal vehicles, and more particularly a light protective plate capable of dissipating at least a part of the kinetic energy of high speed projectiles. This bulletproof plate comprises:
The dressing material is applied to said plurality of foils and the foils thus dressed are laminated together by means of the binder, so as to become delaminated under the action of the impact of high speed bullets.
The plate proposed by the MEDLIN, U.S. Pat. No. 4,352,316, conforms to the results of tests according to which the most efficient means for absorbing the kinetic energy of a projectile is to deform, separate (or delaminate) and penetrate a number of separate armor plating foils.
Worthy of note is also the European Patent CAPPA, EP No. 49 014, although it departs from the scope of the present invention because, contrary to the known technique, the impact resistance is improved by giving to the laminated structure an undelaminable structure, namely a structure which interconnects the different layers of laminated material so as to confer on the whole the capacity of resiliently absorbing the impact due to the projectile without becoming delaminated.
It is a question of an improved non-metal screen which is highly resistant to the impacts of projectiles and of the type formed by the alternating superimposition of thermoplastic resin and textile material layers, which bulletproof protective screen comprises:
The undelaminable structure is obtained by applying rules, most of which are contrary to the usual practice and particularly by providing a negligible or zero adherence, or connection, between the matrix and the fibers, which is obtained by choosing appropriate raw materials for the matrix and the fibers, or by treating these fibers with an agent which makes them impermeable to the matrix.
The foregoing shows:
Furthermore, adaptation to particular shapes, generally curves, of objects to be projected is subordinated to the application of high pressure forming methods (cf. the BOTTINI Patent) or, in some cases, hot forming (this is the case of devices using laminated plastic material panels appropriately reinforced).
To sum up, it may then be concluded that the armor plating devices at present available are of a rigid or semirigid type which, while offering efficient protection, have a certain number of drawbacks, not only in so far as their manufacture, but also in so far as their use is concerned, which limit the applications thereof, particularly: